Armored conductor structure



Dec. 18, 1945. 1. c. SHAFER, JR

ARMORED CONDUCTOR STRUCTURE Filed March 14, 1942 INVEN 70R C. SHAFER, JR.

ATTORNEY Patented Dec. 18, 1945 ARMORED CONDUCTOR STRUCTURE Ira C. Sharer, Jn, Morristown, N. J., assignor to Bell Telephone laboratories, Incorporated, New York, N. Y., a corporation of New York Application March 14, 1942, Serial No. 434,739

16 Claims.

cover the insulated wires as completely as possible to give adequate protection against attacks and, on the other hand, should permit bending of the cable on a comparatively small radius without undue deformation of the armoring, thus permitting the use 01' comparatively small reels; the

structure should be non-tangling and should pre- (sleint a smooth surface to facilitate general han- In accordance with the invention a cable structure of this kind is provided which includes a single layer of armoring tape substantially without any overlapping portions. The layer of armoring is formed of armoring tape of suitable material applied longitudinally of the conductor structure. The armoring forms a continuous layer entirely enclosing the insulated conductor or conductors, except for narrow transverse openings cut in the material at frequent intervals to permit bending of the armored structure without appreciable buckling or the tape material.

The armoring-tape is in effect sectionallzed, the

sections .being separated by narrow openings bridged by small connecting portions to form a continuous structure and the edges 01' the sections are serrated along the seam between tape edges and the teeth along, one edge are made to overlap the opposite edge in a manner to interlock with the tape edges and thus prevent buckling of the tape material along the seam.

The openings in the body portion of the tape are wide enough to prevent crowding of the tape material on the inside of the bend without buckling, when the conductor is bent, and are narrow enough to not unduly expose the insulated conductor when widened on the outside ofthe bend.

'Other features of theinvention'will appear from the following detailed description.

The invention will now be described as applied in a practical embodiment of its various features and reference will be made to the accom- D nyin drawinginwhich:

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Figs. 1 and 2 are perspective views of the' two sides of an armored cable structure with parts broken away to more clearly show the construction;

Fig. 3 is a sectional view of the cable structure in Fig.1;

Fig. 4 is a plan view of the armoring tape used in the structure of Fig. 1;

Figs. 5 and 6 are views showing the cable structure of Fig. 1 bent over each of its flat sides on a small radius.

Referring now to Figs. 1, 2 and 3, the preferred cable structure comprises two conductors l0 and II placed in parallel relation throughout the structure and enclosed in insulating material I2, which may form a single continuous body or may comprise two separate bodies of insulation, one about each conductor. The tape armoring surrounding the insulation l2 comprises an armoring tape 2| of suitable material for protection against gopher attacks. The structure may further include other wrappings, such as 3| and 32, applied about the armoring tape.

This structure, containing two parallel conductors, thus is substantially oval-shaped having two comparatively flat sides and two rounded sides or edges. Whereas the armoring tape shown in Fig. 1 is particularly adapted for the ovalshaped structure, it may readily be adapted for cable structures of circular or other cross section. The armoring tape is shown more in detail in Fig. 4 in the form it is manufactured before application to the cable structure.

The tape 2| presents a fiat surface in effect sub-divided into strip portions 21 by narrow transverse openings 2 5, the strips being interconnected by means of short connecting portions 24 disposed alternately along the edges and along the center line of the tape.

The edge portions of the tape are serrated, one edge having a tooth 26 for each strip portion 21 and the opposite-edge having one tooth intermediate every two strips 21.

The tape 2! is applied longitudinally to one flat side of the conductor structure and return-bent about the two rounded edges to meet and form a seam along the other flat side. The edges of the tape sections will be nearly abutting and the teeth 26 extend across the seam to alternately overlie the opposite'edge of the tape.

From Figs. 1 and 2 it will be observed that on each flat side of the cable the tape presents comparatively long rigid sections separated by narrow transverse openings, the sections on one fiat side being opposite an opening on the other side.

This arrangement is secured by the disposition of the openings 25, alternate openings extending part-way about the cable from the opposite flat sides. As shown in Fig. 1 the seam of the tape passes longitudinally through the sections on the upper side of the cable and the arrangement of the teeth along the seam is such that the sections on this side will be substantially as rigid and free from buckling as those on the other side.

The tape material may be iron or steel or any other suitable composition and may or may not have its surface treated, as bytinning or galvanization. The material may be non-oxidizing and acid resistant to have a longlife in contact with earth and other substances present in the round. a

As will appear from Figs. 5 and 6, the openin s 7 in the tape material permit a slight shift of the tape sections on the outside and the inside of the bend; Without buckling of the material, due to the alternate disposition of rigid sections on the two sides of the structure. 'Ihus at theopening a in Fig. 5, the rigid section b on the inside of the bend causes the opening a to widen atv c on the outside of the *bend, and at the alternatin opening (I the rigid section e on the outside o the bend causes the opening .d to closeup at f of the inside of the bend. Similar actions take place when the conductor structure is bent over the other flat side, as will appear iimm Fig. 6;.

The openings in the completed armcringjshellld be not more than A; .inchand should preterably average about 1 inch inwiclth, This is inopermit laying the cable in the gro nd with .iairly shar curves :or bends without unduly exposing the insulation to gopher attacks when the openings are widened on :the nut-side of the bend. 0n the other hand, openings :of this widthwill als prevent crowding of the tape material on th inside ofthe hand, when the cableis laid or when it is reeled, so that the "armored tape will not be unduly deformed and forced outer position, thereby exposing th insulation to gopher attacks.

.It has been found that by means of these narrow transverse openings, the tape portions forming the main surface of the armoring are free to shift slightly .alongthe cable surface either t widen the openings :or to close thetn up when the cable is bent and therefore the tendency to buckle and expose the underlying cableinsulatlon is .absent when small cables are wound on their .fiat

sides on reels as small as .12 inches in diameter.

It has also been .iound that theintroduction of narrow transverse (openings in the tape material is greatly effective in reducing the usual stiffness of armored cables of this gener l type and easing the handling thereof, both :in factoryand field.

The outer wrappings B] and 32 may be of ilbrous material, such aspa r. and are i a y applied in tape ,form. The wrappingsmay be impregnated or coated with any suitable subconduits, since the cable may be ploughed down 'in' a fast continuous process irom reels oi :rea-

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openin being shorter sonable size. The described structure is readily unbent from the reel and laid in sharp curves Without danger of the tape buckling and unduly opening the seam. With one or two wrappings outside the armoring there is no danger of tangling or catching as the cable leaves the reel, and the cable mayalso readily be manipulated by hand withoutdanger oiiniury.

The described structurelends itself p rticularly to fast manufacturing, as compared with cables having spiral armor tapes, since the lon- V fgitudinal tapes may be applied and locked in position as fast :as the insulated conductors can be produced. 7

Due to the Iact that the finished armoring is in effect brokenup into a large number of small shields or strips separated by narrow openings a degree of flexibility may be secured which is atleastas high as with spirally applied armor tape.

The absence of buckling 01' "the amazing espeeiall-y important iniassllrin tlon against .sonher ettacks. and is attain d by the introduction of the transverse openings in the material which will. Pe mit a sli ht shift n of the armorins material relative to the ainsula tion particularly on the inside 02 t e bend. when the cable is bent, The armored cable may therefore be wound unreasonably small reels, withzoutdanger oi pen-ins up al ngthe seams Thus storage. transportation and laying is greatly .izo-

cilitated. 7

It should he understood that the cehlemey include more than two conductors arranged a sin le layer and may contain more ihanpne such layer of. a pluralty oi c nductors. .A mal conductorcable, circular or diet. is also contemplated within the scope of the mventiou. ilhe two or more conductors may be twisted togethe or otherwise intertwined and a concentric arrangement is also contemplated within the scop of the invention.

What is claimed is;

A 1 1 s insulated condu tor having an armoring tape placed tightly about and longitudinally of said insulated conductor to. term .a. sin- ;gle generally continuous layer enveloping-said conductor, said tape having narrow openings extending transversely of said conductor and disposed at frequent intervals along said co ductor and being adapted to close up on the inside of the bend, when the conductoris bent, thereby substantially preventing buckling or the annexing tape, said transverse openings. being disposed at frequent intervals along any surface line para l l @With the conductor, :each transverse opening be- .ing shorter than the tape width and being laced in the transverse direction relative to "others of said openings-nearly adjacent thereto.

2. A long in ulat d conductor having an armoring tape laced tightly about and lon tudin ly of said i sulated-conductor to tonne g generally continuous layer enveloping said-conductor, said tape having narr w openin s extending transversely of said condu tor and disposed at .trequent intervals :alongsaidoonductor and being adapted to up on the inside of bend. when e conductor is}; nt,..thereby substantially-preventing buckling oi the annexing tape. said openings being-diseased at ,ireeuent inrv ng aid layerand extending... in opposite directions about sa d conductor. eac

than the WP W dth-i 3- a lens. insulatedeonduetor having an armoring tape placed tightly ebolltpndlongltudlnally of said insulated conductor to form a single generally continuous layer enveloping said conductor, said tape having narrow openings extending transversely of said conductor and disposed at frequent intervals along said conductor and being adapted to close up on the inside of the bend, when the conductor is bent, thereby substantially preventing buckling of the armor-ing tape, each of said openings being shorter than the tape width and being displaced half way around the conductor relative to the immediately adjacent openings. 7

4. A long insulated conductor having an armoring tape placed tightly about and longitudinally of said insulated conductor to form a single generally continuous layer enveloping said conductor, said tape having narrow openings extending transversely of said conductor and disposed at frequent intervals along said conductor and being adapted to close up on the inside of the bend, when the conductor is bent, thereby substantially preventing bucklin of the armoring tape, said openings being disposed at frequent intervals along any surface line parallel with the conductor, each transverse opening being displaced in the transverse direction relative to others of said openings nearly adjacent thereto, said tape armoring including small connecting portions across said openings for forming a continuous structure.

5. An elongated insulated conductor, tape armoring placed tightly about and longitudinally of said insulated conductor, the tape of said armoring forming a single generally continuous layer enveloping said conductor and being formed of a continuous series of transverse separated strip portions and including short connecting portions connecting adjacent strip portions to ether into a continuous structure without adding appreciable stiffness to said armoring, said strip portions being sufficiently separated to permit bending of the armored conductor on a small radius without appreciable buckling of the tape material in said strip portions.

6. An elongated insulated conductor, tape armoring placed tightly about and longitudinally oi. said insulated conductor, the tape of said armoring forming a single generally continuous layer enveloping said conductor and being formed of a continuous series of transverse separated strip portions and including short connecting portions connecting adjacent strip portions together into a continuous structure without adding appreciable stiffness to said armoring, said strip portions being sufliciently separated to permit bending of the armored conductor on a small radius without appreciable buckling of the tape material in said strip portions, said strip portions being long enough in the transverse direction to be return bent about the conductor.

7. An elongated insulated conductor, tape armoring placed tightly about and longitudinally of said insulated conductor, the tape of said armoring forming a single generally continuous layer enveloping said conductor and being formed of a continuous series of transverse separated strip portions and including short connecting portions connecting adjacent strip portions together into a continuous structure without adding appreciable stiifness to said armoring, said strip portions being sufficiently separated to permit bending of the armored conductor on a small radius without appreciable buckling of the tape material in said stip portions, said strip portions having edge projections extending across the center line of the seam between tape edges in situ and said edge projections being narrower in the longitudinal direction than the maximum width ofsaid strip portions, the edge projections from opposite sides of the seam being relatively displaced longitudinally of said seam to be interspersed without overlapping of tape material in said projections.

8. An elongated insulated conductor, an ar moring tape placed tightly about and with a seam longitudinally of said insulated conductor and i forming a single generally continuous layer enveloping said conductor, aid armoring tape comprising a continuous series of transverse separated strip portions and small connecting portions connecting adjacent strip portions together into a continuous structure Without adding appreciable stiffness to said armoring, said strip portions being sufiiciently separated to permit bending of the armored conductor on a small radius without appreciable buckling of the tape material in said strip portions, said strip portions being long enough in the transverse direction to be return-bent about the conductor and each of said strip portions having a narrow opening cut lengthwise of the strip and extending transversely of said conductor.

9. An elongated insulated conductor, an armoring tape placed tightly about and with a seam longitudinally of said insulated conductor and forming a single generally continuous layer enveloping said conductor, said armoring tape comprising a continuous series of transverse separated strip portions and small connecting portions connecting adjacent strip portions together into a continuous structur without adding appreciable stiffness to said armoring, said strip portions being sufliciently separated to permit bending of the armored conductor on a small radius without appreciable buckling of the tape material in said strip portions, said strip portions being long enough in the transverse direction to be return-bent about the conductor and the edge portions of said strip portions having edge projections extending across said seam.

10. An elongated insulated conductor, an armoring tap placed tightly about and with a seam longitudinally of said insulated conductor and forming a single generally continuous layer enveloping said conductor, said armoring tape comprising continuous series of transverse separated strip portions and small connecting portions connecting adjacent strip portions together into a continuous structure Without adding appreciable stiffness to said armoring, said strip portions being sufiiciently separated to permit bending of the armored conductor on a small radius without appreciable buckling of the tape material in said strip portions, said strip portions being long enough in the traverse direction to be return-bent about the conductor, the edge portions of said strip portions having edge projections extending across said seam, and said edge projections from opposite sides of the seam being relatively displaced longitudinally of said seam and being long enough to overlap with the opposite edge portion.

11. An elongated insulated conductor, an armoring tape placed tightly about and with a seam longitudinally of said insulated conductor and forming a single generally continuous layer enveloping said conductor, said armoring tape comprising continuous series of transverse separated strip portions and small connecting portions connecting adjacent strip portions together into a continuous structure without adding anpreciablg stifiness to said :armoring, said strip portions being sufiiciently separated to permit bending :of the armored conductor on a small radius without 'appreciableibuckling of the tape material in said strip portion-s, said strip por ti'ons being long enough in the transverse direction to b return-bent about the conductor, the edge portions of said strip portions having edge projections extending across said seam, said edge projections from opposite sides of the seam being relatively displaced longitudinally of :said seam, the edge portions on opposite sides of said seam being interlocked with the edge projections to reduce buck-ling along said seam when the conductor i bent.

12. A long, substantially oval-shaped armored conductor structure having two opposed comparatively fiat sides and two opposed rounded sides and being particularly adapted for bending over said flat sides on a small radius, including a plurality of insulated conductors and tape armoring closely surrounding said insulated conductors for protection against attacks byrrodents, said tape armoring forming a continuous layer enveloping said plurality of conductors with =a lonenveloping said plurality of conductors with a longitudinal seam disposed along one of said flat sides, said tape armoring having a series of short rigid body sections disposed (along each of said flat sides and separated by narrow transverse spaces, said narrow spaces in both of said series of body sections being extended through the armor material around both of said rounded sides to further reduce buckling of the tape material.

14. .A long, substantially oval-shaped armored conductor structure having two opposed coauparatively flat sides and two opposed rounded sides and being particularly adapted m 'bending over said flat sides on a small radius, including a plurality of insulated conductors .for ,protection against attacks by rodents, said tape arimoring forming a continuous layer enveloping said plurality of conductors with a longitudinal seam disposed along one of said flat sides, and said tape armoring having a series of short rigid body sections along each of said flat sides and separated by narrow transverse spaces, the said narrow spaces on opposite na-t sides extending transversely to have their end portions interspersed.

, 15. A long, substantially oval-sl 1aped armored conductor structure having two opposed compan atively ifiat sides-and two opposedrounded :sides' and being particularly adapted for bending over said flat sides on a small radius, includinga plurality of insulated conductors and tape armor- .ing closely surrounding said insulated "conductors for protection against attacks by rodents,

, said tape armoring forming continuous layer sides and :being particularly-adapted for bending over said flat sides on a small radius, including a plurality of insulated conductors and tape armoring. closely surrounding said insulated conductors for protection against attacks by rodents, said tape armoring forming a continuous layer enveloping said plurality of conductors with ,a,

longitudinal seam disposed along one of said .tlat sides, said tape armoring having a series of short rigid body sections along :each of said flat asides, said body sections along opposite tfla-t sides being relatively displaced in the longitudinal direction and said seam extending through the rigid sections on one of said flat sides.

IRA c. SHAFER, JR. 

